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更新时间:2015-12-7 9:34:00 来源:纽约时报中文网 作者:佚名

Ask Well: Ebola and Sex

Question: Why hasn’t it been publicized and become a public health warning that male Ebola survivors can harbor Ebola virus in their semen for several months after recovery?


Answer: From the first Ebola outbreak in 1976 until this year, most experts believed the virus was never sexually transmitted because there had never been a documented case.


That was true even though there was one known precedent. In 1967, lab workers in Marburg, Germany, and other European cities fell seriously ill after dissecting African green monkeys imported from Uganda; seven people died. Their disease, now known as Marburg hemorrhagic fever, is caused by a filovirus like Ebola. Six weeks after one worker recovered, his wife fell ill. Genetic matches were not possible then, but sex with him was her only known risk factor, according to Dr. Daniel G. Bausch of the World Health Organization, who has studied virus levels in victims and survivors.

这话没错,不过,其实也算是有一个广为人知的先例存在的。1967年,德国马尔堡市和欧洲其他城市的实验室工作人员在解剖从乌干达进口的非洲绿猴后就患上了重病,最后七人死亡。这种病如今被称为马尔堡出血热(Marburg hemorrhagic fever),由一种很像埃博拉病毒的丝状病毒引起。在其中一名工作人员康复六周后,他的妻子病倒了。当年尚不可能做基因比对,但她唯一的已知风险因素就是与他发生过性行为,世界卫生组织(World Health Organization, W.H.O.)的丹尼尔·G·鲍施(Daniel G. Bausch)博士说,他研究了病亡者和幸存者的病毒水平。

But there is now one clear-cut case of Ebola transmission through semen — first reported this spring and recently detailed in The New England Journal of Medicine — and other possible cases. As a result, the W.H.O. and the Centers for Disease Control and Prevention have changed their guidelines. The changes got relatively little publicity because fear of Ebola waned after cases fell sharply.

然而,现在已经有明确的病例表明埃博拉病毒可通过精液传播(今年春天首次报道,最近在《新英格兰医学杂志》[The New England Journal of Medicine]详细报道),还出现了其他的疑似病例。因此,WHO和美国疾病控制和预防中心(Centers for Disease Control and Prevention, CDC)修订了有关指南。但由于埃博拉病例锐减后人们的恐惧也随之减弱,上述修订并没有得到充分的宣传。

In the documented case, Ruth Tugbah, a 44-year-old food seller in Liberia’s capital, Monrovia, developed Ebola and died. Before she fell ill, Liberia had detected no new infections for three weeks.

在上述第一例有记载的病例中,患者名叫露丝·图格巴(Ruth Tugbah),44岁,是利比里亚首都蒙罗维亚的一名食品销售商,因埃博拉出血热而死亡。在她发病之前,利比里亚已有三周未检出新发感染了。

Investigators eventually concluded that she had been infected by her boyfriend, who had been released from an Ebola treatment center months before. Genetic matching showed that his virus and hers were so closely related that he must have been the source, and traces of viral genetic material were still in his semen 175 days after he first fell ill. (He had a second sex partner shortly before Ms. Tugbah, a 45-year-old woman whom he did not infect, according to a C.D.C. report.)


Last month, a study of 93 male survivors in Sierra Leone found that nearly half had viral genetic material in their semen. The amounts tended to decline as time passed, but several still had it nearly nine months later. It is not known whether the men were actually infectious as the test detected only viral fragments and whole virus was not grown out in cell cultures.


For these reasons, the C.D.C. and W.H.O. now advise male survivors to use condoms every time they have sex for at least six months and possibly indefinitely. They can safely stop only after their semen is found to be virus-free in two tests taken a week apart.


There is no known case of a female survivor infecting anyone through sex.


Experts currently believe that only male survivors present a threat of Ebola transmission through sex. Men who are newly infected and just developing the symptoms of fever, nausea and diarrhea will have high loads of virus in their blood, vomit and feces, but not in their semen.


That is because some parts of the body, including the eyes, the brain and the testes, are “immunologically privileged.” Protected by membranes and bathed in their own special fluids, they are harder for viruses and bacteria to invade. But, once their defenses are breached and the pathogen is inside, it often takes the body longer to clear it out there than to clear the same invader from blood, tissue and most other organs.


Scientists do not know whether the bulk of the virus hides in the testicles, which produce sperm, or the prostate, which produces semen.


Female survivors are not thought to infect others through sex. While growing fetuses are somewhat immunologically privileged, vaginal walls and fluids are not.


There are now about 17,000 survivors of the West Africa Ebola outbreak that began in 2013. The new studies have added to stigma and discrimination, particularly against the men.


“The rumor that survivors infect women is a huge problem,” Dr. Bausch said.


At the same time, he said, “a fair number” of male survivors are having problems getting or keeping erections. There is no official estimate of erectile dysfunction among survivors, he said, but men “frequently report it” in private discussions with doctors. It is less common than joint pain, which at least 80 percent of all survivors report, and uveitis, or inflammation inside the eye, which is reported by 20 to 50 percent of survivors in different studies.